[Postoperative nausea and vomiting: rational algorithms for prevention and treatment based on current evidence].

Postoperative nausea and vomiting (PONV) constitutes a major unpleasant symptom in the postoperative period. The prevention of PONV is judged equally important as the prevention of postoperative pain. Therefore, a working PONV-algorithm should be as self-evident as the approach to prevent and treat postoperative pain. None of the currently available pharmacological interventions is able to totally abolish PONV. However, using a multimodal approach with the combination of various antiemetic interventions, a substantial reduction or even elimination of PONV is already feasible. As a rule of thumb, each effective antiemetic intervention will lead to a relative risk reduction of approximately 30 %. Well documented interventions in terms of the aforementioned efficacy are the administration of ondansetron 4 mg, dexamethasone 4 mg, droperidol 1,25mg and dimenhydrinate 62 mg, as well oral Aprepitant. Metoclopramide may play a role for instance in a multimodal approach. Apart from the administration of antiemetics, the avoidance of inhalational anaesthetics by using propofol is associated with a comparable risk reduction. In general, using a risk-dependent approach, e.g. based on a simplified risk score, allows to avoid administering antiemetics to patients at low risk. However, due to the difficulties associated with the implementation of risk-score based algorithms and the inherent weaknesses of clinical risk scores to predict PONV in an individual patient, a general (multimodal) approach seem to be justified as well. Considering the fact that the currently available antiemetics are associated with few side effects, the administration of prophylactic antiemetics should not be associated with a high hurdle in the clinical setting. In case of any doubts regarding the individual risk, it seems justified to expand the (multimodal) prophylaxis rather than to wait until PONV occurs and impairs patient comfort.